Designed by Alexander Kartveli, then Republic's chief designer, the P-47 was built in response to the USAAF's recognition that it needed a heavier fighter than those presently in production or on the drawing boards in 1940. Kartveli adopted an unconventional approach to designing this aircraft. Recognizing from the outset that it would need not only a large powerplant but a turbocharger or supercharger, Kartveli began by designing the duct system that provided the turbosupercharger with air, and then building the fuselage of the aircraft around that system. This allowed him to place the bulk of the turbosupercharger in the tail of the aircraft, where its weight could counterbalance that of the enormous engine, a Pratt & Whitney 'Double Wasp' powerplant. This engine was a 2,000 HP radial engine, with eighteen cylinders in two rows. One of the recognizable features of the P-47 is the turbocharger exhaust outlet under the rear of the aircraft. This placement actually added a few MPH to the plane's top speed, generated by the few pounds of thrust produced by the exhaust flow -- a primitive jet assist.

Although this allowed Kartveli to put a large and powerful engine into the aircraft, it also generated some 'features' of the airplane that would prove deadly later on in combat. First, the aircraft ended up being extremely heavy once the engine, systems, tanks for the amount of fuel it required and armament were added -- so heavy that the early P-47 had a reputation for 'folding its wings' when pulling out of a dive under high enough G loads. The mainspar would break, allowing the wings to 'fold up' on either side of the unfortunate aircraft, and it would go into the ground. Despite this, it could still outdive most other aircraft in the theater; enemies that attempted to escape the P-47 by diving were in for a rude shock.

Thunderbolts were known for absorbing terrific amounts of damage and flying their pilots home; this is a characteristic it shares with its descendant the A-10 Thunderbolt II. Pilots told stories (with evidence) of losing four feet of wing, massive amounts of hydraulics and more, and still returning home across the English Channel.

The armament was impressive as well -- eight 50-caliber (half-inch) machine guns mounted in the wings, as well as up to 2,500 pounds of ordnance slung under the fuselage (or an optional drop tank for additional range).

All this weight came with a penalty, and that was in low- and medium-altitude climb performance. The P-47 excelled at bomber escort (except for its relatively limited range) but had to be careful not to be lured too low, as it would find itself outmatched trying to get back to altitude.

To supplement The Custodian's writeup above, it is not true that the P-47 had poor climb performance overall. Early models of the Jug were equipped with a 12 foot, four bladed propellor. Though large for the time, it proved too small to take full advantage of the R-2800's power. Beginning with the P-47D-22RE and P-47D-23RA the early propellor was replaced with a very large (13 feet in diameter) propellor. The new prop was so wide it was referred to as the "paddle blade" propellor. (either a Hamilton Standard Hydromatic 24E50-65 or a Curtiss Electric C542S). The new propellor made take-off and landing more interesting, as it only permitted one foot of ground clearance, but it gave an enormous boost to the Thunderbolt, particularly in rate of climb. Retrofit kits were made available and added to earlier P-47's because the change proved so effective.

In the book Thunderbolt! by Thunderbolt aceRobert S. Johnson and aviation author Martin Caiden Johnson describes how dramatic the effect was. In mock dogfights wit the British Supermarine Spitfire the older Thunderbolts had been readily outclimbed, with the paddle blade the situation was immediately reversed, with the Thunderbolt easilty outclimbing the Spitfire 9. Johnson himself stated: ". . . . never again did a Focke Wulf outclimb me."

Caiden later quoted the story from Thunderbolt in his book Fork Tailed Devil: The Story of the P-38 in order to demonstrate enormous possible impact of a single design change. The paddle blade propellor made the Jug into a climber, and it was not surpassed by any German aircraft until the ME-262 jet fighter, which was in another league entirely.